1. Field of the Invention
The present invention relates to an image pickup apparatus that determines a scene-dependent in-focus position while being on standby for photographing, and relates to a control method for the image pickup apparatus and a storage medium storing a program therefor.
2. Description of the Related Art
To reduce a time lag in execution of photographing, a recent digital camera (image pickup apparatus) has a continuous AF function for displaying a through-image on an image display and continuously performing AF (auto-focus) for focus adjustment, while being on standby for photographing.
The continuous AF function is advantageous in that framing can easily be performed by continuous focusing and in that, if an in-focus position has been attained when or before a release button is depressed, a time lag can be reduced by scanning over a predetermined range from the in-focus position.
There has also been proposed a technique for reducing a time lag by determining a scene and by determining a scanning direction to restrict a scan range based on the determined scene (see, for example, Japanese Laid-open Patent Publication No. 2006-023383). Another proposed technique reduces a time lag by restricting a photographing condition so as to correspond to a selected one of scenes set in advance in an image pickup apparatus (see, for example, Japanese Laid-open Patent Publication No. 2001-311977).
However, with the continuous AF function adapted to first maintain the visual quality of a through-image, the entire scene is not scanned, even if a scene change takes place. When the release button is depressed immediately after a scene change, therefore, the entire scene must be scanned, resulting in a long time lag which poses a problem.
With the technique disclosed in Japanese Laid-open Patent Publication No. 2006-023383, in which the focus lens is driven from its stop position to a direction decided according to the determined scene, a problem is posed that a time lag is much prolonged, if the in-focus position is on the side opposite from the focus-lens driving direction with respect to the lens stop position.
With the technique disclosed in Japanese Laid-open Patent Publication No. 2001-311977 in which the in-focus position at photographing is fixed, a problem is posed that satisfactory focusing cannot be achieved depending on object state.